Respiration is performed in a circuit in breathing equipment, especially in gas masks, to reduce the weight and to prolong the service life, and only the amount of oxygen having been consumed is added from a pressurized gas reserve. To prevent the carbon dioxide (CO2) breathed out from accumulating in the circuit to nonphysiological levels, an absorber with an absorbent, which removes the CO2 from the breathing circuit, is present in the circuit. Prior-art absorbents consist of one or more alkali hydroxides and contain or consist especially of calcium hydroxide. Heat and moisture are generated during the chemical reaction taking place between the CO2 and the absorbent, and this may lead to an increase in the breathing gas temperature and to discomfort for the person respirated through the breathing equipment. Thus, temperatures that were up to 15° C. higher than the particular ambient temperature were measured after the absorber, and the breathing gas is saturated with moisture. It was therefore proposed that gas masks that are used for a prolonged period of time of several hours be equipped with a breathing gas cooler.
The use of paraffin or a salt as a coolant for such breathing equipment is disclosed in DE 879 651 B; the evaporation temperature or the melting point is between 40° C. and 180° C. here, and the alkali cartridge is surrounded by the coolant.
As an addition to DE 879 651 B, DE 916 384 B shows as a characterizing feature that the cooling jacket is formed from at least one layer of corrugated board provided especially with continuous longitudinal openings, which are covered by smooth board layers on both sides, so that channels are formed, which facilitate the absorption of cooling liquid by the jacket.